The decreasing order of reactivity of the following compounds towards nucleophilic substitution ( S N 2 ) is:

Step-by-step solution

Rate   of   S N 2   reation   α   Electrophilicity   of   alkyl   carbon   α   1 Steric   crowding   on   R - X S N 2 reaction depend upon - I ,   - M , effect. - I , - M group increases the rate of S N 2 reaction.